QT学习笔记之十 Ticker

无聊学习着……

写一个Ticker,练习下事件触发

部分代码如下:

ticker.h

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
#ifndef TICKER_H
#define TICKER_H
#include <QtGui/QWidget>
namespace Ui
{
class Ticker;
}
class Ticker : public QWidget
{
Q_OBJECT
public:
Ticker(QWidget *parent = 0);
~Ticker();
void setText(const QString &newText);
QString text() const ;
QSize sizeHint() const;
protected:
void paintEvent(QPaintEvent *event);
void timerEvent(QTimerEvent *evnet);
void showEvent(QShowEvent *event);
void hideEvent(QHideEvent *event);
private:
Ui::Ticker *ui;
QString tickerText;
int offset; //时间间隔
int timerID; //定时器ID
};
#endif // TICKER_H

ticker.cpp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
*#include <QtGui>
#include "ticker.h"
#include "ui_ticker.h"
Ticker::Ticker(QWidget *parent)
: QWidget(parent), ui(new Ui::Ticker)
{
ui->setupUi(this);
offset = 0;
timerID = 0;
}
Ticker::~Ticker()
{
delete ui;
}
/**
设置文本
*/
void Ticker::setText(const QString &newText)
{
tickerText = newText;
update();
updateGeometry();
}
/**
获取文本内容
*/
QString Ticker::text() const
{
return tickerText;
}
/**
设置Widget大小
*/
QSize Ticker::sizeHint() const
{
return fontMetrics().size(0,text()); //fontMetrics(): Returns the font metrics for the widget's current font
}
/**
绘制事件
*/
void Ticker::paintEvent(QPaintEvent *)
{
QPainter painter(this);
int textWidth = fontMetrics().width(text());
if (textWidth < 1)
return ;
int x = -offset;
while (x < width()) {
painter.drawText(x,0,textWidth,height(),Qt::AlignLeft | Qt::AlignVCenter,text()); //绘制文本
x += textWidth;
}
}
/**
定时器事件
*/
void Ticker::timerEvent(QTimerEvent *event)
{
if (event->timerId() == timerID) {
++offset;
if(offset >= fontMetrics().width(text()))
offset = 0;
scroll(-1,0); //向左滚动一个像素
} else {
QWidget::timerEvent(event);
}
}
/**
显示事件
*/
void Ticker::showEvent(QShowEvent *)
{
timerID = startTimer(30); //Starts a timer and returns a timer identifier, or returns zero if it could not start a timer.
}
/**
隐藏事件
*/
void Ticker::hideEvent(QHideEvent *)
{
killTimer(timerID);
timerID = 0;
}

界面截图如下:

image

可以自动向左滚动…(怎么感觉像楼下显示电费的….尴尬了)


继续无聊的暑假….